/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package a.annotation.proguard.classfile.attribute.annotation;

import proguard.classfile.*;
import proguard.classfile.attribute.annotation.visitor.ElementValueVisitor;
import proguard.classfile.visitor.MemberVisitor;

/**
 * This abstract class represents an element value that is attached to an annotation or an annotation default. Specific
 * types of element values are subclassed from it.
 *
 * @author Eric Lafortune
 */
public abstract class ElementValue implements VisitorAccepter {
    /**
     * An extra field for the optional element name. It is used in element value pairs of annotations. Otherwise, it is
     * 0.
     */
    public int u2elementNameIndex;

    /**
     * An extra field pointing to the referenced <code>Clazz</code> object, if applicable. This field is typically
     * filled out by the <code>{@link proguard.classfile.util.ClassReferenceInitializer}</code>.
     */
    public Clazz referencedClass;

    /**
     * An extra field pointing to the referenced <code>Method</code> object, if applicable. This field is typically
     * filled out by the <code>{@link proguard.classfile.util.ClassReferenceInitializer}</code>.
     */
    public Method referencedMethod;

    /**
     * An extra field in which visitors can store information.
     */
    public Object visitorInfo;

    /**
     * Creates an uninitialized ElementValue.
     */
    protected ElementValue() {}

    /**
     * Creates an initialized ElementValue.
     */
    protected ElementValue(int u2elementNameIndex) {
        this.u2elementNameIndex = u2elementNameIndex;
    }

    /**
     * Returns the element name.
     */
    public String getMethodName(Clazz clazz) {
        return clazz.getString(u2elementNameIndex);
    }

    // Abstract methods to be implemented by extensions.

    /**
     * Returns the tag of this element value.
     */
    public abstract char getTag();

    /**
     * Accepts the given visitor.
     */
    public abstract void accept(Clazz clazz, Annotation annotation, ElementValueVisitor elementValueVisitor);

    /**
     * Applies the given visitor to the referenced method.
     */
    public void referencedMethodAccept(MemberVisitor memberVisitor) {
        if (referencedMethod != null) {
            referencedMethod.accept(referencedClass, memberVisitor);
        }
    }

    // Implementations for VisitorAccepter.

    public Object getVisitorInfo() {
        return visitorInfo;
    }

    public void setVisitorInfo(Object visitorInfo) {
        this.visitorInfo = visitorInfo;
    }
}
